Selectable Gain Amplifier Switching for Glitch-Free Output

Solution Overview

Problem

Amplifier systems face abrupt and undesirable changes in output voltage when switching between different gain settings, leading to voltage disturbances or glitches, especially when transitioning between high voltage, low resolution and low voltage, high resolution ranges.

Innovation Solution

The implementation of a switch-selectable amplifier system with a primary and auxiliary gain circuit path, a summing circuit, and logic circuitry that allows for seamless transition between gain settings by setting the auxiliary input signal equal to the primary input signal, ensuring no aberrations at the output by making the auxiliary signal gain equal to the difference between the primary and secondary signal gains, and using feedback control to maintain a target signal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If gain setting is changed in a switched amplifier, then the voltage range or resolution is improved, but output voltage glitches occur

Engineering Contradiction:

Improvevoltage rangeVSAvoidoutput voltage glitches

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by pre-calculating and storing compensation values in lookup tables before gain switching occurs. The compensation value corresponding to the new gain setting is retrieved and applied in advance to counteract the expected glitch, thereby preventing output voltage disturbances during gain transitions.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by monitoring the output voltage during gain transitions and using this information to adjust the compensation signal. The feedback mechanism detects actual glitch behavior and fine-tunes the compensation values, ensuring accurate glitch cancellation while maintaining signal integrity.

Inventive Principle:

Principle #23Feedback

2Measurement precision

If gain setting is changed in a switched amplifier, then the resolution is improved, but output voltage glitches occur

Engineering Contradiction:

ImproveresolutionVSAvoidoutput voltage glitches

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by pre-calculating and storing compensation values in lookup tables before gain switching occurs. The compensation value corresponding to the new gain setting is retrieved and applied in advance to counteract the expected glitch, thereby preventing output voltage disturbances during gain transitions.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by monitoring the output voltage during gain transitions and using this information to adjust the compensation signal. The feedback mechanism detects actual glitch behavior and fine-tunes the compensation values, ensuring accurate glitch cancellation while maintaining signal integrity.

Inventive Principle:

Principle #23Feedback

3Reliability

If multiple gain circuit paths are used, then glitch-free operation is achieved, but device complexity increases

Engineering Contradiction:

Improveglitch-free operationVSAvoidcircuit paths

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the amplifier into multiple gain circuit paths (first gain circuit path and second gain circuit path) that can be selectively activated. Each path is optimized for specific gain ranges, allowing smooth transitions without glitches while maintaining manageable complexity through modular design.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an auxiliary gain circuit path as an intermediary element that bridges the transition between different main gain paths. This auxiliary path provides a smooth handoff mechanism that eliminates abrupt changes and glitches during gain switching, reducing overall system complexity by using a dedicated transition path.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11824506B2Glitch reduction technique for switched amplifiers having selectable transfer gain

Publication Date: 2023.11.21 ANALOG DEVICES INT UNLTD CO

AI summary

An amplifier circuit comprises a first gain circuit path configured to provide a first signal gain to an input signal, a second gain circuit path configured to provide a second signal gain to an input signal, an auxiliary gain circuit path configured to provide an auxiliary signal gain to an auxiliary input signal, wherein the auxiliary signal gain is equal to the first signal gain minus the second signal gain, a summing circuit configured to sum the second gain signal path and the auxiliary signal path, and logic circuitry configured to change an output of the circuit between the first gain circuit path and the sum of the second gain signal path and the auxiliary signal path, and set the auxiliary input signal equal to the input signal before the changing.